1. Technical Field
The present invention generally relates to thin film transistor arrays and, more particularly, to a thin film transistor substrate and a method for its manufacture.
2. Related Art
A thin film transistor (TFT) substrate is generally used as a circuit board for independently driving each pixel in a liquid crystal display (LCD) or an organic light emitting display (OLED) device. The thin film transistor substrate includes a scanning signal line (or a gate signal line) transmitting a scanning signal, an image signal line (or a data signal line) transmitting an image signal, and a thin film transistor connected to the gate signal line and the data signal line.
With an increase in size and resolution of the liquid crystal display, resistance of the metal wiring such as the gate signal line and the data signal line formed in the thin film transistor substrate is increased such that an RC (resistor-capacitor time constant) delay is generated. To reduce the resistance of the metal wiring, a method using copper as a metal having low resistance has been developed.
The copper wiring reacts with the organic layer, however, such that the organic material is adsorbed on the surface of the signal wiring. If this phenomenon is generated on the gate electrode when forming the gate wire made of the copper material, display deterioration may occur.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.